Diazotype photoprinting materials



Patented Aug. 5, 1952 2,606,117 DIAZOTYPE rno'roram'rmc MATERIALS Thaddeus J. Trojnar, Binghamton, N. Y., assignor to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application June 5, 1947, Serial No. 752,835

8 Claims.

This invention relates to improvements in diazotype photoprinting materials and in the process of making the same.

Photoprinting materials sensitized with diazotype compositions (i. e. compositions containing light-sensitive diazo compounds which are selfcoupling, or which are used with a suitable coupling component, yielding latent images on exposure to light of locally varied intensity, which can be developed [e. g. with alkaline vapors] to form direct positives) have adapted themselves to many uses because of their versatility and ease of handling.

One field of use oifering attractive and varied possibilities for application of these materials is the manufacture of signs, posters, display cards and the like. However, use of diazotype mate rials for this purpose has been limited by reason of the fact that the decomposition products formed in the development of diazotype compositions tend to discolor badly when subjected to prolonged exposure to sunlight or ultra-violet light. Moreover, in reproducing photographs the results are often inferior to those produced with conventional silver halide emulsions by reason of the tendency of diazotype materials to form images having excessively contrasting highlights and choked-up shadows.

It is an object of this invention to provide diazotype photoprinting materials suitable for use in making posters, signs and display cards, wherein discoloration of the various developed copies, when exposed to sunlight or ultra-violet light, is minimized or eliminated, and wherein the contrast of photographic images produced therewith can be controlled within wide ranges to yield softened highlights and open shadows, as well as a wide range of control of gloss. In conjunction with the foregoing object, it is an object of this invention to provide diazotype photoprinting material yielding copies which are durable on exposure to rain, moisture or other adverse Weather conditions.

In one modification of the invention, it is object to provide photo-sensitive printing materials which are adapted to yield highly decorative color effects, having, for example, a background of any desired color, and an image of a different color.

In accordance with my invention, a carrier layer is provided for the light-sensitive diazo composition, containing a lustrous powdered metal pigment, such as aluminum, bronze or copper bronzing powder, tinted or natural, incorporated in the layer. The metallic pigment is 2 preferably incorporated in a translucent filmforming vehicle, applied as a coating to a suitable supporting base, such as paper, cardboard, cloth or metal, or may be incorporated in a translucent or transparent plastic which may be cast, molded or drawn to form a carrier layer as such, or it can be laminated or otherwise mounted on a suitable supporting base. The vehicle employed for the metallic pigment can be made of waterresistant or waterproof film-forming material, or of a plastic, such as a lacquer or film or cellulose acetate, cellulose acetobutyrate, ethyl cellulose, or of natural or artificial resins, whereby the prints obtained are adapted to be displayed outdoors, and to withstand the effects of adverse weather conditions, particularly rain and moisture, and are likewise characterized by excellent durability for handling.

The aforesaid carrier layer or coating containing the metallic pigment is sensitized with a light-sensitive diazo composition in accordance with any of the methods known to the art. For example, the layer is advantageously treated on its exposed surface with a solution of a lightsensitive diazo compound, such as p-diazo-N,N- dimethyl aniline, or p-diazo-N,N-diethyl-m-phenetidine, together with a suitable coupling component such-as resorcinol or phloroglucin, together with suitable stabilizers, in a solvent adapted to impregnate the aforesaid carrier layer. The solvent is then allowed to evaporate, leaving the surface of the carrier layer or coating impregnated and sensitized with the diazotype composition. Or, if desired, the diazotype composition can be incorporated in the film-forming or plastic material of the carrier layer together with the metallic pigment.

When colored or tinted background effects are desired, a dyestuff, substantive to the vehicle of the carrier layer and preferably fast to light, can be used to color the carrier layer at any convenient stage in its formation or subsequent processing.

I have discovered that when the photoprinting material of my invention, containing a metallic pigment in the carrier layer, is exposed to light of locally varied intensity (e. g. under a photographic positive) .and developed, for example, by treatment with an alkaline vapor such as gaseous ammonia, a print is obtained having open shadows and softenedhighlights constituting a highly superior reproduction of the photographic subject matter. While it is not intended to limit the inventionby any theory of operation, it appears probable that this advantageous effect re- 3 sults from diiiusion of the exposing light by the metallic particles in the vicinity of the sensitizing composition. By varying the amount of metallic pigment in the carrier layer, the contrast of the image can be controlled within wide limits. In addition, inclusion of a metallic pigment in the carrier layer has a flatting effect on the prints produced which can be varied, depending upon the proportion of metallic pigment employed. Thus, the improvement of my invention affords a means for controlling the gloss of the resulting copies.

Moreover, I have found that the prints obtained with the photoprinting material of my invention can be subjected to prolonged exposure to sunlight or ultra-violet light without objectionable discoloration or yellowing of the background,

thus rendering diazotype materials available. for general use in the manufacture of display cards, signs and posters. Apparently, the metallic pigment contained in the carrier layer protects the decomposition products of the diazotype sensi tizing composition from the effects of light, and also masks-such discoloration as may occur at the surface of the print.

The high reflectivity of the metallic pigments employed in the carrierof my-photopri'nting material yields copies having ahighly decorative appearance, particularly pleasing to the eye. Artistic effects canbe produced by coloring the vehicle of the carrier layer with appropriate dyestuffs, and employing a sensitizing composition which yields a contrasting'color, produced, for example, in varying degrees of saturation, so that it combineswith the-background coloration to yield a picture of variable hue.

My invention will be more fully understood from the following examples, which illustrate but do not limit the invention:

Example I 5 g. of aluminum bronzing powder were dispersed in 100 cc. of a cellulose acetate lacquer (in which the cellulose acetate wa 52-55% acetylated, and suitably plasticized), and the resulting composition. was applied to form a coating layer on clay-coated paper stock. After drying, the resulting, coating layer was sensitized by treatment with a solution containing p-diazo- N,N-dimethyl aniline and resorcinol, togethertial discoloration upon exposure. to ultra-violet. light for three or six hours, while a control sample. prepared in the same manner. but without in.-

cluding the aluminum pigment in the carrier. layer, was badly discolored under the same. conditions.. a

ExampleZ 2.5" g. of aluminum bronzing powder were dispersed in cellulose acetate lacquer of the same composition as that described in Example 1, and the resulting mixture similarly applied to paper stock as a support. The resulting layer was sensitized in the. same. manner as in the preceding example with arsensitizingsolution containing p-diazo N;N-diethyl m phenetidine and phloroglucin, together with a suitable stabilizer in a solvent of the type hereinbefore disclosed. A print or copy made with the resulting material in the same manner as in Example 1, and similarly exposed to ultra-violet light, showed very little discoloration, whereas a control sample prepared in the same manner but without incorporation of aluminum pigment in the cellulose acetate lacquer, showed excessive yellowing upon similar exposure to light.

Example 3 the bronze powder in the cellulose acetate lacquer showedno substantial yellowing upon prolonged exposure to ultra-violet light.

Example 4 Samples of cellulose acetate lacquer of the type employed in the preceding examples were pre pared containing respectively 5 g. and 2.5 g. of aluminum powder, and also containing no metallic pig-ment, and these samples were applied to a paper base to form a carrier layer whichv was sensitized with the diazotype composition of Example l. Upon exposure of the resulting photoprinting material under photographic positives, and development with ammonia vapor, it was found that the print obtained on the lacquer coating containing no aluminum pigment had excessively contrasting highlight regions, choked-up shadows and high gloss; the print obtained on lacquer containing, 2.5% aluminum powder had less contrast inthe highlights, more open shadows and less gloss, while the print obtained on the lacquer containing 5%. aluminum powder had low contrast, extended latitude and open shadows, and was of'relatively fiat appearance.

Example 5 7 Example 6 V; g. of a light-fast yellow cellulose acetate dyestuff' ('e. g. Celliton Fast Yellow G Powder) Was substituted in the procedure of Example 5 for the blue-green-dyestuif'employed therein and the resulting coating. was sensitized with the diazotype solution of Example 1'. The resulting photoprinting material yielded copies having a yellow-brown image on ayellow or. gold metallic background of exceedingly pleasing appearance.

. Example?- The' procedures of- Examples-1 and 3 were'repeated, except that a sheet of cellulose acetatefilm having athickness of 0.005 inchwas employed as a suDportingbase-instcad of paper. Copies obtained with they-resultant photoprinting material possessed the same superior properties and. advantages as described the foregoing examples, showing-no substantial discoloration on the prolonged exposure of ultra-violet light, and yielding images having softened highlights and open shadows.

Variations can be made in the structures and procedures described in the foregoing examples without departing from the scope of the invention. Thus, supporting base materials other than paper or cellulose acetate film can be used including, for example, cloth, other plastics, cardboard or metal. Likewise, other water-resistant vehicles may replace cellulose acetate in the carrier layer, for example, other cellulose esters or ethers, or natural or artificial water-repellent resins. However, when exposure to moisture or adverse weather conditions is not contemplated, water-soluble or hydrophilic colloid vehicles can replace the aforesaid waterproof materials as the carrier layer vehicle. In order to produce photoprinting material yielding a colored background, various dyestuffs can be employed which are substantive to the particular carrier vehicle used. The proportion of metallic pigment employed in the coating composition is subject to considerable variation, depending upon the result desired. In general when aluminum or bronze powder is used, a proportion of the order shown in the examples has been found satisfactory.

I claim:

1. Diazotype photoprinting material comprising a light-sensitive layer having a light-sensitive diazo composition and a lustrous powdered metal pigment co-mingled in said layer.

2. Diazotype photoprinting material comprising a light-sensitive layer of translucent filmforming material containing a light-sensitive diazo composition and a lustrous powdered metal pigment co-mingled in said layer.

3. Diazotype photoprinting material comprising a layer of film-forming material containing a lustrous powdered metal pigment, and a lightsensitive dia zo composition impregnating at least the surface portion of said layer.

4. Diazotype photopririting material comprising a supporting base, a coating of water-resist ant lacquer containing a lustrous powdered metal pigment in a translucent film-forming vehicle, and a light-sensitive diazo composition impregnating at least the surface portion of said coating.

5. Diazotype photoprinting material comprising a light-sensitive layer of translucent filmforming material containing a light-sensitive diazotype sensitizing composition including an azo coupling component and a light-sensitive diazo compound stabilized against coupling prior to development, and a lustrous powdered metal pigment incorporated in said layer.

6. Diazotype photoprinting material as defined in claim 2, wherein said translucent film-forming material is tinted with a light-fast dyestuff.

7. Developed diazotype photoprinting material comprising a layer of translucent film-forming material containing a lustrous powdered metal pigment, an azo dye image, residual azo couplin component, and light-decomposed diazo compound residues in the metal pigment-containing portion of said layer.

8. Developed diazotype photoprinting material as defined in claim 7 wherein the translucent filmforming material of said layer further contains a light-fast dyestufi tinting the layer.

THADDE'US J. TROJNAR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 640,137 Kuhn Dec. 26, 1899 694,227 Ahrle Feb. 25, 1902 731,831 Ahrle June 23, 1903 1,651,136 Lang Nov, 29, 1927 1,762,033 Schmidt et a1 June 3, 1930 1,961,348 Goedtler June 5, 1934 2,018,657 Bennett Oct. 29, 1935 2,043,309 Stone June 9, 1936 2,100,063 Zahn Nov. 23, 1937 2,121,013 Brown June 21, 1938 2,216,736 Carothers Oct. 8, 1940 FOREIGN PATENTS Number Country Date 21,537 Great Britain 1902 402,737 Great Britain 1932 401,898 Great Britain Nov. 23, 1933 536,714- Great Britain May 23, 1941 

1. DIAZOTYPE PHOTOPRINTING MATERIAL COMPRISING A LIGHT-SENSITIVE LAYER HAVING A LIGHT-SENSITIVE DIAZO COMPOSITION AND A LUSTROUS POWDERED METAL PIGMENT CO-MINGLED IN SAID LAYER. 